Coarse and fine adjustment means

ABSTRACT

A coarse and fine adjustment device especially for focusing a lens system in which both the coarse and fine adjustment are transmitted by two levers pivotally connected together. The coarse or fine adjustment levers are moved by control means which may comprise screw-threaded pins, cam surfaces or an inclined plane acting upon the levers. Only one of the levers is in actual contact with the element to be moved.

United States Patent [191 Czapek Jan. 15, 1974 COARSE AND FINEADJUSTMENT MEANS [75] Inventor: Andre Louis Czapek, Le Perreux,

France [73] Assignee: Societe dOptique, Precision Electronique etMechanique-Sopelem, Paris, France [22] Filed: May 9, 1972 [21] Appl.N0.: 251,735

[30] Foreign Application Priority Data May 24, 1971 France 71.18559 [52]US. Cl 74/479, 74/522, 350/84 [51] Int. Cl G05g 11/00 [53] Field 01'Search 74/522, 479; 350/84 [56] References Cited FOREIGN PATENTS ORAPPLICATIONS 12,208 5/1902 Great Britain 350/84 Primary Examiner-AllanD. l'letrmann Att0rneyWilliam B. Kerkam, Jr.

[5 7 ABSTRACT A coarse and fine adjustment device especially forfocusing a lens system in which both the coarse and fine adjustment aretransmitted by two levers pivotally connected together. The coarse orfine adjustment 1evers are moved by control means which may comprisescrew-threaded pins, cam surfaces or an inclined plane acting upon thelevers. Only one of the levers is in actual contact with the element tobe moved.

7 Claims, 4 Drawing Figures 1 COARSE AND FINE ADJUSTMENT MEANS Theinvention relates to a coarse and fine adjustment device particularlybut not exclusively for use in focusing a microscope.

In a microscope, focusing is carried out by producing two movements atwidely different rates and of widely different amplitude: one, the fastor coarse movement, whose amplitude is of the order of some tens ofmillimetres, is for approximate focusing; the other, the slow or finemovement, which is over a shorter distance (at most a few millimetres),is highly reduced and permits focusing with a precision of a fraction ofa micron.

In the prior art these two movements generally act on two differentguides or slides which may or may not be superimposed. However, it isbecoming common for both movements to act on a single slide, since thisobviously increases the eventual rigidity of the movable element andalso simplifies the microscope mechanically. Existing solutions forcombined fast and slow movements acting on a movable element guided by asingle slide are of two types:

I. reduction of the coarse movement control;

2. micrometric adjustment of the coarse movement control.

These solutions have the following principal disadvantages: The coarsecontrol must be coupled precisely to the movable element in solutions oftype 1), to obtain the maximum benefit from the fine slow movement; andprecise auxiliary guiding means are required for the coarse movementcontrol.

An object of the invention is to provide a solution which does not havethe disadvantages of the known devices.

Accordingly there is provided a coarse and fine adjustment devicecomprising first and second levers in pivotal relationship to each otherand to a base frame, each lever being adapted to be operated by aseparate control means engaging said base frame to transmit a coarse orfine adjustment to a movable element, wherein said levers act asmultiplying or reducing members for their respective control means.

In one embodiment, the controls for the levers comprise screws attachedto the stand.

In another embodiment of the invention, the coarse movement iscontrolled by means of an inclined plane moving beneath the coarsemovement transmission levet, and the fine movement is controlled bymeans of a screw.

In a further embodiment of the invention, the coarse and fine movementsare produced by means of cams.

Advantageously, accordingto one feature of the in vention, the jointsupporting the assembly comprising the two levers is formed by aresiliently deformable systern of the spring hinge type.

Further features and advantages of the invention will arise out of theensuing description which illustrates, by way of example only, variousembodiments of the invention with reference to the accompanyingdrawings.

In the drawings:

FIG. 1 is a diagrammatic perspective view of a first embodiment of theinvention;

FIG. 2 is a perspective view of a variant of the embodiment shown inFIG. 1;

FIG. 3 is a perspective view of a second embodiment; and

FIG. 4 is a perspective view of another embodiment of the invention.

In the drawings reference 10 designates a movable element, which may forexample be a stage, a revolving nose-piece or the eyepiece/objectiveassembly, guided by a straight slide. A first lever 11, for producingthe slow or fine movement, is pivoted on the fixed portion or stand 13by means of a pivot pin 12. The movements of this lever (with the objectof producing fine movement of the movable element 10) are controlled inthis embodiment by a screw 14.

A second lever 15 is pivoted on the lever l 1 by means of a pin 16. Itbears on a point 17 at which the control means act on this lever 15. Thecontrol means in this example are a screw 18 attached to the stand 13.This lever 15 controls the movement of the slide-guided movable element10.

The device operates as follows.

1. Coarse movement Operation of the control 18 causes the lever 15 toturn on the pivot pin 16, which at this moment is fixed, and moves theelement 10 by a distance:

1: being the movement due to the control 18, d being the length of thelever 15, and 0 being the distance separating the point 17 at which thecontrol acts on the lever 15 from the pin 16.

2. Fine movement Operation of the control 14 causes the lever 11 to turnon the pin 12 mounted on the stand 13. The joint 16, common to thelevers 11 and 15 therefore moves. This movement is transmitted to themovable element 10 by the lever 15, which pivots about the point 17 atwhich the coarse control 18 acts, this point now being fixed. Themovement Y of the movable element 10 corresponding to movement y of thecontrol 14 is then:

a being the distance between the pivot pins 12 and 16, and

b being the distance separating the pin 12 from the point 19 at whichthe control 14 acts on the lever 11.

The levers 11 and 15 make it possible not only to transmit the coarseand fine movements to the movable element 10 without any play, but alsoto select the desired reduction ratios for the controls 14 and 18. Ingeneral a transmission ratio of at least unity will be selected for thefast movement. For the slow movement, on the other hand, thetransmission ratio may be less than or equal to unity, which permitssimplification of the control 14.

A variant of the embodiment described above with reference to FIG. 1 isillustrated in FIG. 2. Since this variant differs from the embodimentshown in FIG. 1 only in the shape of the levers l1 and 15 and in thevarious joints, it will not be described.

In the embodiment shown in FIG. 3, the coarse movement (arrow M iscontrolled by means of an inclined plane, or wedge 22, moving beneath aroller 21 mounted on an element 25 attached to the lever 15. The lever15 transmits this coarse movement to the element 10 by way of a roller23 mounted on the end of the lever 15 and a pin 24 fixed to the movableelement.

The fine movement control comprises a simple screw, representeddiagrammatically by the arrow M moving a block 26 which bears on anabutment 27 mounted on the end of the lever 11.

In this embodiment the joint 12 (equivalent to the pin 12 in FIGS. 1 and2) which supports the assembly comprising the two levers l1 and 15, andwhich must therefore be very rigid and permit only slight rotation, mayadvantageously comprise a resiliently deformable system of the springhinge type, formed for example by an assembly of two leaves such as 20.

In the embodiment shown in FIG. 4 the coarse and fine movements arecontrolled by cams 34 and 30 respectively. The lever 15 bears on the cam34 (which is operated by a control 33) by way of the roller 21. To avoidtransmitting undesirable movements to the movable element 10, the lever15 acts on this element by way of an idle roller 23.

A roller 31 mounted on the lever 11 bears on a cam 30 rotated by a wormand worm-wheel operated by a knob 32. In this embodiment the joint 12'is a spring hinge composed of leaves 35 and 36.

I claim:

1. A coarse and fine adjustment device for a movable element comprisinga first lever acting at one extremity on the movable element, said firstlever being articulated about an adjustable first axis for coarseadjustment of the movable element, a second lever in pivotalrelationship with said first lever and pivoted to a base frame, andcontrol means for said second lever engaging said base frame for fineadjustment to the movable element.

2. A device as claimed in claim 1 wherein one of said levers beingpivoted to the base member by a pivot pin the other of said leverscontacting the movable element.

3. A device as claimed in claim 1 including a resiliently deformablespring hinge assembly supporting said levers.

4. A device as claimed in claim 1 said control means being a screwthreaded element.

5. A device as claimed in claim 1 the adjustable first axis of saidfirst lever being controlled by an inclined plane member.

6. A device as claimed in claim 1 wherein at least one of said levers iscontrolled by cam means.

7. A device as claimed in claim 1 wherein said first lever acts on themovable element through an idle roller.

1. A coarse and fine adjustment device for a movable element comprisinga first lever acting at one extremity on the movable element, said firstlever being articulated about an adjustable first axis for coarseadjustment of the movable element, a second lever in pivotalrelationship with said first lever and pivoted to a base frame, andcontrol means for said second lever engaging said base frame for fineadjustment to the movable element.
 2. A device as claimed in claim 1wherein one of said levers being pivoted to the base member by a pivotpin the other of said levers contacting the movable element.
 3. A deviceas claimed in claim 1 including a resiliently deformable spring hingeassembly supporting said levers.
 4. A device as claimed in claim 1 saidcontrol means being a screw threaded element.
 5. A device as claimed inclaim 1 the adjustable first axis of said first lever being controlledby an inclined plane member.
 6. A device as claimed in claim 1 whereinat least one of said levers is controlled by cam means.
 7. A device asclaimed in claim 1 wherein said first lever acts on the movable elementthrough an idle roller.